1. Field of the Invention
The present invention relates to a data communication apparatus and a data communication method in which data of low speed specifications are transmitted using a transmission line of high speed specifications, and a program for implementing the method.
2. Description of Related Art
Personal computers are generally equipped with an IEEE 1394 serial bus that is an interface of high speed specifications, or a USB (Universal Serial Bus) that is an interface of medium speed specifications, and data of low speed specifications such as MIDI (Musical Instrument Digital Interface) data are transmitted and received via these interfaces. For example, the data transfer rate of the IEEE 1394 serial bus is 100–400 Mbps, and the data transfer rate of the USB is approximately 10 Mbps. On the other hand, MIDI Standards prescribes that 8 bit data (including 1 bit for stop bit) should be transferred at a reference clock frequency of 31.25 kHz , that is, the data transfer rate is approximately 300 kbps.
When MIDI data are generated using a sequence program on a personal computer, complicated control change data or data of a number of channels exceeding 16 channels, that is, data whose required processing speed exceeds the above-mentioned reference clock according to MIDI Standards, can be frequently generated. Even such data whose required processing speed exceeds the reference clock according to MIDI Standards can be transmitted to an external apparatus using the IEEE 1394 serial bus or the USB. However, if the external apparatus is a so-called MIDI apparatus (an apparatus according to MDI Standards), it may fail to perfectly receive data transmitted thereto at a transfer rate in excess of the reference clock according to MIDI Standards. This can lead to inadequate data processing.